Talk to them all the time, conversations about what is going on around them, take it to a deeper level, not just what tee-shirt do they like when choosing clothes, but where was it made, what was it made of, how where the workers treated, why should we care?
Keep a cheap globe by the TV, and look up every country mentioned
Be active in the community with them - take them on litter picks, demonstrations, explain why every time
Expose them to music and art, and follow their interests and preferences
music lessons do not need to be one-to-one, they can start an instrument in a group and see how they like it
Sport, what ever is cheapest, sporting skills are transferable if they find another sport they are more interested in later on, My football crazy son started his sporting life at free basketball sessions put on by the local council in school holidays.
Teach them to be articulate, teach them complicated adult words, dont just talk down to them, help them find the right word if they are struggling.
Teach them to talk clearly, and stand tall and look people in the eye, and smile